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Lotus 43
Lotus 43
Lotus 43
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Lotus 43
CategoryFormula One
ConstructorTeam Lotus
Designers
PredecessorLotus 33
SuccessorLotus 49
Technical specifications[1][2]
ChassisAluminium monocoque
Suspension (front)top rocker arms, lower wishbones, inboard coil springs over dampers
Suspension (rear)reverse lower wishbones, twin radius arms, coil springs over dampers, anti-roll bar
EngineBRM P75
2,996 cc (183 cu in) H16 Naturally aspirated
TransmissionBRM T82 6-speed manual
Weight563 kg (1,241 lb)
FuelEsso
TyresFirestone
Competition history
Notable entrantsTeam Lotus
Notable driversUnited Kingdom Peter Arundell
United Kingdom Jim Clark
United Kingdom Graham Hill
Debut1966 Belgian Grand Prix
Last event1967 South African Grand Prix
RacesWinsPodiumsPolesF/Laps
51100
Constructors' Championships0
Drivers' Championships0

The Lotus 43 was a Formula One racing car designed by Colin Chapman and Maurice Philippe[3] for the 1966 season. Hampered by its heavy and unreliable BRM engine, it won only one race, the 1966 United States Grand Prix.

Concept

[edit]

The Lotus 43 was partially based on the Lotus 38 Indycar, designed by Len Terry, due to Lotus's experience at Indy with larger engine capacity and tyre/suspension setup. The car was designed in this way in response to new F1 regulations which came into force in 1966, which increased the engine capacity to 3 litres. Along with newer, wider tyres better able to handle the power of the larger engines, the need for a more robust design was obvious.[4]

Cosworth were developing a new engine for Lotus, the DFV, to be introduced for the 1967 Formula One season, and in the meantime Chapman made a deal for use of the BRM P75 H16 engine. The P75 on paper was technically advanced and powerful, and Chapman had hopes that it would power his cars to another successful season.[5]

The first sign of trouble was when the H16 engine arrived at the Team Lotus factory in Hethel, Norfolk and it required four men to lift it from the truck. The engine proved to be overweight, unreliable and was unable to produce the promised power.[6]

Engine problems aside, the 43 chassis was considered an excellent design[according to whom?] and elements of it were used in its 1967 successor, the far more successful Lotus 49, including the use of the engine as a stressed structural member which bore weight and to which the rear suspension was attached.

Racing history

[edit]

1966

[edit]

The car was supposed to debut at the 1966 Monaco Grand Prix, driven by Peter Arundell, but it was unavailable. Its first outing at the following Belgian Grand Prix ended during practice, when the engine gave out.[1]

The 43 reappeared at the Italian Grand Prix but retired with gearbox failure. Clark then won the United States Grand Prix at Watkins Glen, the only race win for the P75 engine, using a spare engine loaned by the BRM team. However, gearbox failure again led to the 43's retirement from the final race of the season, the Mexican Grand Prix.

1967

[edit]

In 1967 the 43 made its final appearance at the South African Grand Prix at the Kyalami circuit, where Clark and new team mate Graham Hill both retired their cars.

Only two cars were built and were later sold to Robert Lamplough and Jock Russell, who fitted them with 4.7 litre Ford V8 engines and competed in Formula 5000 events.

  • Lotus 43 at the BTCC Knockhill 2014
    Lotus 43 at the BTCC Knockhill 2014
  • Lotus 43 being demonstrated in 2014
    Lotus 43 being demonstrated in 2014

Complete results

[edit]

Formula One World Championship results

[edit]

(key)

Year Entrant Engine Tyres Drivers 1 2 3 4 5 6 7 8 9 10 11 Points WCC
1966 Team Lotus BRM P75 3.0 H16 F MON BEL FRA GBR NED GER ITA USA MEX 13‹The template Smallsup is being considered for deletion.› 1 5th
Peter Arundell DNS Ret
Jim Clark Ret 1 Ret
1967 Team Lotus BRM P75 3.0 H16 F RSA MON NED BEL FRA GBR GER CAN ITA USA MEX 62 8th
Jim Clark Ret
Graham Hill Ret

^1 Total points scored by all Lotus-BRM cars, including 4 points scored by drivers of Lotus 33 variants.
^2 Total points scored by all Lotus-BRM cars, including 6 points scored by drivers of Lotus 33 variants.

Non-championship Formula One results

[edit]

(key)

Year Entrant Engine Tyres Drivers 1 2 3 4
1966 Team Lotus BRM P75 3.0 H16 F RSA SYR INT OUL
Jim Clark DNS

PC simulation

[edit]

A driveable, detailed reconstruction of the Lotus 43 (with matching car physics) appeared in 2007 in the freely-available '66 Mod' for the PC-based racing simulation Grand Prix Legends.

References

[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Lotus 43

View on Grokipedia
from Grokipedia
The Lotus 43 was a Formula One racing car developed by for the 1966 season, designed by as an interim solution ahead of the engine's arrival, and notable for incorporating the BRM Type 75 H16 as a stressed chassis member. This 3.0-litre H16 engine, derived from two 1.5-litre V8s arranged in an H-pattern with separate crankshafts geared together, produced approximately 375–420 horsepower but weighed around 305 kg including the gearbox and clutch, resulting in a high center of gravity and poor compared to rival V8 and V12 units. The car's , partially based on the design, was adapted for wider tyres and revised suspension to accommodate the engine's size and demands, marking an early use of the power unit as a in . In its racing career, the Lotus 43 appeared in five Grands Prix between 1966 and 1967, driven primarily by , but suffered from frequent mechanical failures including engine seizures and gearbox issues that limited its competitiveness. Its sole victory came at the 1966 at Watkins Glen, where capitalized on retirements by leading rivals to secure Team Lotus's only win that season and the H16's unique distinction as the only 16-cylinder engine to triumph in a race. The model was quickly superseded by the more successful in 1967, leaving the 43 as a of ambitious but flawed innovation in Formula One's transitional 3.0-litre era.

Development

Background

In 1966, underwent a significant change, doubling the maximum from 1.5 liters to 3.0 liters to usher in an era of greater power and performance. This shift, often dubbed the "return to power," prompted teams to seek new engine solutions, as existing suppliers like were unwilling or unable to quickly scale up to the larger capacity. Faced with tight development timelines for the new formula, Lotus team principal opted to adapt the chassis from the successful IndyCar, which had proven effective with larger engines and robust suspension setups at . This decision allowed Lotus to leverage existing engineering while modifying the platform for demands. Designers and Maurice Philippe played key roles in the adaptation, with Philippe focusing on integrating the chassis around the selected powerplant to maintain Lotus's emphasis on lightweight construction and handling agility. To power the Lotus 43, Chapman forged a with BRM to supply the innovative P75 H16 as a temporary measure, stemming from delays in the development of the V8, which was earmarked for the following year. The H16 was initially expected to deliver around 420 horsepower at over 10,000 rpm, promising a competitive edge through its unique configuration of two stacked flat-eight cylinders geared together. However, the faced substantial challenges, including excessive , mechanical complexity with multiple camshafts and crankshafts, and reliability issues that hindered its potential despite the high hopes.

Design features

The Lotus 43 employed an aluminum chassis adapted from the Indy car design, re-engineered for Formula One's narrower track requirements and higher torsional rigidity demands while retaining the original's lightweight construction principles. Key dimensions included a of 2,438 mm, and front and rear track widths of 1,524 mm, allowing for agile handling on European circuits. Aerodynamic considerations centered on a low-profile bodywork configuration to integrate the exceptionally tall BRM H16 engine without compromising the car's streamlined silhouette. This resulted in a basic, wingless design emblematic of mid-1960s F1 aesthetics, with glass-fibre reinforced plastic panels for the nose and engine cover to minimize drag and enhance airflow over the chassis. The engine's height dictated a raised cowling, but the overall form prioritized simplicity and low center of gravity over complex downforce generation. The braking system featured outboard disc brakes at all four wheels. Wheels measured 15 inches in diameter, fitted with Firestone racing tires in sizes optimized for grip and durability on Grand Prix tracks, helping achieve the car's curb weight of 563 kg for superior power-to-weight performance. Fuel system integration reflected Esso sponsorship, with a centrally mounted positioned behind the driver to optimize and maintain rearward bias under varying fuel loads during races. This placement enhanced stability, particularly as fuel consumption altered the center of mass over long stints.

Technical specifications

Chassis and suspension

The Lotus 43 employed an aluminium monocoque tub as its core structural element, constructed from riveted and bonded panels to deliver a yet rigid framework capable of withstanding high cornering loads. This incorporated three bulkheads for enhanced torsional strength, contributing to the car's overall dry weight of approximately 567 kg. The was derived from the Indy car, adapting its proven architecture for Formula 1 demands while integrating the within the tub for efficient packaging. The front suspension followed established Lotus principles with upper rocker arms, lower wishbones, and inboard dampers to optimize camber control and ride compliance during high-speed circuits. At the rear, the setup utilized reversed lower wishbones, twin radius arms for lateral location, outboard dampers, and an adjustable , allowing fine-tuning for varying track conditions. This configuration supported the car's mid-engine layout while maintaining geometric consistency under load. Steering was handled by a rack-and-pinion system with tuned for quick response and precise feedback, aiding driver confidence in tight corners. Overall, the and suspension combination was engineered for neutral handling balance, prioritizing high-speed stability through its low polar and stiff structure. However, the substantial rear weight bias introduced by the BRM H16 —tipping the scales at 232 kg—affected dynamic equilibrium, leading to potential understeer in low-speed maneuvers despite the inherent design strengths.

Engine and drivetrain

The Lotus 43 was powered by the BRM P75 H16 engine, a naturally aspirated unit with a displacement of 2,996 cc configured as two stacked 180-degree V8s—essentially two flat-eight cylinder banks one above the other—with separate crankshafts geared together for synchronization. This complex layout, featuring an aluminium alloy block and heads, DOHC valvetrain with two valves per cylinder, and gear-driven camshafts, was designed to deliver high-revving performance in the new 3.0-liter Formula One formula. The engine produced approximately 420 hp at around 10,500 rpm, making it one of the most potent power units available at the time, though its output was somewhat hampered by development delays. Despite its theoretical advantages, the BRM P75 faced significant challenges that undermined its effectiveness. At 232 kg, it was substantially overweight compared to rival V8 and V12 engines, which typically weighed around 150 kg, contributing to the Lotus 43's overall balance issues. The 16-cylinder design also led to high fuel consumption, requiring larger tanks and more frequent pit stops, while reliability was plagued by excessive vibration from the geared crankshafts and overheating due to the compact of the stacked banks. These problems often resulted in mechanical failures during testing and races, limiting the engine's potential. Fuel delivery was handled by a Lucas mechanical port fuel injection system, which provided precise metering to each for optimal efficiency in the high-revving H16. This setup, combined with Lucas transistorized ignition and a single 10 mm sparking plug per , supported the engine's 11.5:1 and dry-sump lubrication, though it added to the unit's maintenance demands. The drivetrain featured a BRM T82 six-speed integrated with the final drive unit, delivering power to the rear wheels. This setup, while robust in theory, inherited some of the engine's issues, necessitating careful during shifts. The overall combination weighed around 306 kg for the engine and gearbox assembly, further emphasizing the packaging challenges. Maintaining the H16 required frequent rebuilds—often after just a few hours of running—due to wear from and stresses, along with specialized tools to access the stacked cylinder banks and geared components. These complexities made the a high-risk choice for , selected as an alternative to the emerging V8.

Racing history

1966 season

The Lotus 43 made its competitive debut at the at Spa-Francorchamps, entered by with the BRM H16 engine. Peter Arundell was scheduled to drive the new car but did not start after an engine seizure during practice, while teammate raced the older Lotus 33-Climax but retired on the formation lap following an accident in wet conditions. This early reliability setback highlighted the challenges with the complex H16 powerplant, which suffered from overheating and mechanical fragility right from the outset. The car skipped the at due to persistent transmission issues that required extensive rework, preventing from fielding it. The Lotus 43 was also absent from the at due to these ongoing transmission problems. Further troubles plagued the at , where Arundell retired on lap 4 after gear selection problems caused the distributor drive to shear. These non-finishes stemmed primarily from the H16's overheating tendencies and the gearbox's inadequate strength under race loads, prompting ongoing testing and tweaks by the Lotus team, including efforts to revise the cooling system for better heat management. The at offered a brief glimmer of potential, with qualifying strongly in the Lotus 43, but he retired on lap 59 due to gearbox failure. The season's highlight came at the at Watkins Glen, where delivered the Lotus 43's—and the BRM H16's—sole victory. Qualifying second just 0.1 seconds off pole, dropped to fourth at the start but methodically climbed through the field, taking the lead on lap 56 after Jack Brabham's engine failure; he maintained control to win by over 30 seconds, completing all 108 laps without issue in a dominant display that masked the car's earlier woes. At the season-ending , qualified second but retired on lap 9 with gearbox failure. Despite the promise shown at Watkins Glen, the Lotus 43's 1966 campaign was marred by unreliability, with only that single finish across five entries. Team Lotus scored 13 points in the Constructors' Championship via the US win and other minor contributions, securing fifth place overall. Clark, blending results from both the Lotus 43 and 33-Climax, ended the drivers' standings in sixth with 16 points, underscoring his skill in extracting performance from troubled machinery.

1967 season

The Lotus 43 made only a single appearance during the 1967 World Championship, at the season-opening at on 2 January. Team entered two examples of the car, assigning the new chassis 43/2 to and the older chassis 43/1 to , who had joined the team that year as Clark's teammate. Both drivers qualified with mechanical issues including a leaking fuel bag, with Clark in 3rd place (1:29.0) and Hill 15th (1:32.6). In the race, Clark retired on lap 22 due to engine failure in his BRM H16 power unit, while Hill lasted until lap 64 before withdrawing with suspension failure. Neither car finished, resulting in zero points for the Lotus 43 entries. These retirements underscored the persistent reliability challenges of the heavy and complex BRM H16 engine, which had plagued the car since its debut. With the arrival of the revolutionary and its later in the season, shifted focus entirely to the new model starting from the , demoting the 43 to non-competitive reserve status. The South African Grand Prix marked the Lotus 43's final competitive outing, bringing an end to Lotus's experimentation with H16 power in Formula One as the team embraced the more reliable and potent DFV era.

Results

World Championship Grands Prix

The Lotus 43 participated in five World Championship Grands Prix across 1966 and 1967, with entries in the French, Italian, United States, Mexican, and South African races.
Grand PrixDateCircuitDriverGrid PositionFinish PositionPoints Scored
French GP3 July 1966Peter Arundell17Retired (lap 3, gearbox)0
Italian GP4 September 19663Retired (lap 58, gearbox)0
United States GP2 1966Watkins Glen21st9
Mexican GP23 19662Retired (gearbox)0
South African GP2 January 19673Retired (engine)0
South African GP2 January 196715Retired (accident)0
In total, the Lotus 43 made six entries in Grands Prix, achieving one win at the 1966 , one podium finish, and five retirements, with no fastest laps recorded. The Lotus 43 scored points in only one race, earning 9 points for from Jim Clark's victory in the 1966 ; all other entries yielded 0 points. These results contributed to the Lotus-BRM entry finishing 5th in the 1966 Constructors' Championship with 13 points overall (including points from other Lotus-BRM chassis). In 1967, the Lotus 43 scored no points, and the Lotus-BRM combination placed 8th in the Constructors' Championship with 0 points attributable to the model.

Non-championship races

The Lotus 43 saw limited participation in non-championship events, primarily in 1966 following its late-season debut, with no recorded entries in 1967 as shifted focus to races and the development of the Lotus 49. These appearances highlighted the car's ongoing reliability challenges with the BRM H16 engine, resulting in no race finishes or competitive results. The sole non-championship outing for the Lotus 43 occurred at the Gold Cup meeting at Oulton Park on 17 September 1966. Entered for , the car was used only in practice sessions before the BRM engine failed, forcing Clark to revert to a Lotus 33-Climax for the race itself, where he finished second. This incident underscored the engine's fragility outside of controlled Grand Prix conditions.
EventDateLocationDriverResult
Gold Cup17 Sep 1966Oulton Park, UKNon-start (engine failure in practice)
Overall, the Lotus 43's non-championship record was marked by minimal success, with zero completions in its only attempted event, further emphasizing the reliability issues that plagued the car throughout its brief career.

Legacy

Later modifications and preservation

Following the end of its career, both examples of the Lotus 43 were modified for Formula 5000 competition. In 1968, chassis 43/1 and 43/2 were converted by preparer Ken Nichols at the request of South African Robs Lamplough, with the original BRM H16 engines removed and replaced by 4.7-litre Ford Shelby V8 units to comply with F5000 regulations. The conversions saw limited success in and European F5000 events. Chassis 43/1 was acquired by Scottish driver Jock Russell and campaigned through 1969, achieving a best finish of fourth place at the Gran Premio de at Jarama in April but otherwise recording lower placements such as 11th at and 12th at Oulton Park, before retiring from competition. Chassis 43/2 remained with Lamplough for the 1969 Guards F5000 Championship, where it scored a fourth at but suffered retirements and lower results including 11th at Oulton Park and 12th at ; it was later upgraded to a 5-litre Ford Boss 302 V8 and raced sporadically in 1970 by driver Mike Woolley, with a best of 16th at . Only two Lotus 43s were ever constructed, making their preservation a key aspect of 1960s heritage. Chassis 43/1 underwent an eight-year restoration to original F1 specification starting in the early , led by experts Hall & Hall with input from former BRM personnel, and was completed in 2013 under the ownership of British historic racer Andy Middlehurst. It has since appeared in non-competitive demonstrations at events such as the 2013 —where it participated in a tribute parade, marking the first public outing of an H16-powered 43 since 1967—and the 2016 Oulton Park Gold Cup. Chassis 43/2 resides in a private collection, with its last recorded activity in 2017 (as of the latest available records), though it has not been noted in historic outings since. These surviving cars exemplify the audacity of mid-1960s grand prix design, particularly the challenges of integrating complex power units like the BRM H16, and they occasionally feature in historic displays to highlight Lotus's innovative era under .

Cultural impact and simulations

The Lotus 43 endures as a of ambitious but flawed in Formula 1, embodying 's willingness to experiment with cutting-edge concepts at the expense of practicality. Powered by the innovative yet cumbersome BRM H16 engine, the car highlighted the risks of prioritizing power and novelty over reliability, ultimately prompting Lotus to abandon such heavy designs in favor of lighter, more efficient alternatives. This pivot directly influenced the development of the , which adopted the V8 engine and revolutionized F1 by combining chassis innovation with dependable performance, ushering in an era of dominance for the team. In media, the Lotus 43 has appeared in documentaries exploring 1960s F1 and Chapman's innovations, often underscoring its role in Jim Clark's career. For instance, the 2018 DriveTribe production Remembering Jim Clark & the Lotus 43 details the car's sole Grand Prix victory at the 1966 United States Grand Prix, emphasizing Clark's exceptional skill in overcoming its mechanical shortcomings. Similarly, footage from the Goodwood Festival of Speed showcases the surviving Lotus 43 in action, highlighting the H16 engine's distinctive sound and historical significance. Books on Chapman, such as Karl Ludvigsen's Colin Chapman: Inside the Innovator (2021), reference the Lotus 43 as part of Chapman's engine experimentation, noting its integration of the BRM H16 alongside other powerplants like the Ford 1172 and Cosworth DFV. The car's legacy extends to digital simulations, where it has been recreated for historic racing enthusiasts. The 2007 '66 Mod for includes the Lotus 43 with accurate BRM H16 physics and 3D modeling, enabling players to simulate the 1966 season, including Clark's Watkins Glen triumph among 16 chassis-engine combinations. In modern platforms like , community-created skins adapt the Lotus 43's 1966 livery—complete with period-correct sponsors and Clark's number 22—onto 1960s-era F1 models such as the EVE F1B, facilitating virtual historic races. Culturally, the Lotus 43 is iconic for the H16 engine's unparalleled uniqueness, frequently cited in analyses of F1's engine experimentation during the 3-liter formula era. This H16 configuration—consisting of two stacked 1.5-litre flat-8 engines delivering a broad band from 4,000 to 9,500 rpm—represented a daring departure from dominant V8s and V12s, offering high power (around 420 hp) but plagued by excessive weight and complexity. Though limited to sporadic appearances in 1966–1967 before being supplanted by more practical designs, it exemplifies the era's innovative spirit and remains a touchstone for discussions on the balance between engineering boldness and race-winning viability.

References

  1. https://formula143.org/2021/05/30/1966-lotus-43-clark/
  2. https://www.racefans.net/2015/06/28/lotus-43brm-h16-2012-goodwood-festival-speed/
  3. https://www.roadandtrack.com/motorsports/a21632666/lotus-43-history-jim-clark/
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  6. https://www.motorsportmagazine.com/archive/article/july-1966/24/lotus-brm-f1-type-43/
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  10. http://members.madasafish.com/~d_hodgkinson/brm-e-H16.htm
  11. https://www.youtube.com/watch?v=8h4EBDn5Hg0
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  20. https://www.grandprix.com/gpe/rr150.html
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  22. https://www.formula1.com/en/results/1966/drivers
  23. https://www.oldracingcars.com/lotus/43/
  24. https://www.motorsportmagazine.com/archive/article/february-1967/14/grand-prix-of-south-africa-2/
  25. https://www.formula1.com/en/results/1967/races/244/south-africa/qualifying.html
  26. https://www.oldracingcars.com/f1/results/1967/south-africa/
  27. https://www.motorsportmagazine.com/archive/article/april-2024/130/lotus-49-race-car-of-the-century-shortlist/
  28. https://www.goodwood.com/grr/f1/video-this-f1-lotus-43-has-an-h16-engine/
  29. https://www.oldracingcars.com/f1/results/1966/france/
  30. https://www.oldracingcars.com/f1/results/1966/italy/
  31. https://www.oldracingcars.com/f1/results/1966/usa/
  32. https://www.oldracingcars.com/f1/results/1966/mexico/
  33. https://www.formula1.com/en/results/1966/awards/fastest-laps
  34. https://www.formulaonehistory.com/results/1966-f1-constructors-championship-standings/
  35. https://www.f1-fansite.com/f1-results/1967-f1-championship-standings/
  36. https://www.motorsportmagazine.com/articles/single-seaters/f1/lotus-43-brm-returns-oulton-park/
  37. https://www.oldracingcars.com/f1/results/1966/oulton-park-gold-cup/
  38. https://www.oldracingcars.com/f5000/lotus/
  39. https://www.ultimatecarpage.com/chassis/1232/Lotus-43-BRM-43-1.html
  40. https://www.oldracingcars.com/lotus/43/2
  41. https://www.historicracingnews.com/Article/The-Lotus-43-and-its-Mighty-16-Cylinders-/655
  42. https://www.youtube.com/watch?v=x-HDK92PNhE
  43. https://www.evropublishing.com/en-us/products/colin-chapman-inside-the-innovator
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  45. https://www.overtake.gg/downloads/lotus-43-1966-skin.1496/
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